Document Version of Lab Report here:

How a Candle Works

Purpose:

The purpose of this experiment is to find out how a candle burns, and calculate the heat associated with the combustion reaction.

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Materials:

1. Candle
2. Ruler
3. Aluminum foil
4. Balance
5. Matches
6. Temperature probe
7. Glass tube
8. Heater
9. Syringe (and other materials required for capturing and measuring gas)

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Hypothesis:

I knew that both the wick and the wax contributed to the burning flame because it didn’t seem likely for the wax to burn by itself and the wick looked like it would burn easily. The wax is had to have a purpose as well because the amount of wax decreases as a candle burns so it must be used up through the process of burning.

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Procedures (Click on each title for experiment results and recordings)

Burning Wick by Itself

1. Break the wax apart carefully
2. Extract the wick
3. Burn one end of the wick to see what will happen
4. Record

Heating Wax

1. Take the broken wax and heat it in a beaker
2. Observe any gas that may be coming out
3. Try sticking a burning candle above the wax
4. Record

Burning Condensed Wax Vapor after Candle is Put out

1. Put out a burning candle after burning for a few minutes
2. Extend a burning match into the gray condensed vapor that comes out of the candle
3. Record

Comparing Decrease of Wax to the Increase in Heat

1. Place candle on top of a piece of aluminum foil
2. Measure combined mass
3. Burn candle for five minutes
4. Measure heat throughout the experiment at different parts of the flame
5. Measure combined mass at the end
6. Record details throughout
7. Burn candle on a balance until mass has decreased by 10 grams
8. Calculate amount of carbon dioxide and water create based on atomic weights of the products and reactants
9. Try to calculate the specific heat capacity of each of the substances based on temperature
10. Form equation for the complete balanced combustion of the candle wax

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Self Evaluation

What can be assumed to be true?
Now we are quite sure that both wax and wick are indeed necessary for a candle to burn properly. We can make this conclusion because from two of the experiments 1 and 2 we can see that without one or the other, a candle cannot burn like it is intended to. From experiment 2 and 3 we can conclude that conclude that it is actually the wax that acts as a fuel that is burning. The “black smoke” emitted is a slightly condensed visible version of wax vapor and fire will allow fire to travel through it easil
The Science behind the Experiments
Based on reliable sources such as the textbook and the internet, we can conclude the following:
The wick is a highly absorbent material that will absorb the melted wax and bring it up to the flame where the wax will continue to burn. The wick is what is initially burned but wax is used to continue and enlarge the flame.
The wax that reaches the flame will continue a combustion reaction where it will combine with oxygen and burn to create water vapor and carbon dioxide. The Combustion formula that I created is as follows: 2C20H42(s)+61O2(g)=40CO2(g)+42H2O(g)

Modifications and further Investigations
There are some possible modifications to further investigate the combustion reaction of candles:

• Use a certain amount of burning wax and wax only to heat water and calculate or have a better understanding of the chemical potential energy of wax.
• Connect one end of a glass tube to a candle flame and see if fire can burn from the other end since wax vapor at a burning state is also present there.